In the past, there has been known a system which is designed to display an image of the workpiece surface which is cut by a ball end mill together with the tool path at the time of cutting (for example, see Patent Literature 1). Further, there has been known a system which is designed to subtract a model of the shape of the sweep of the ball end mill from a 3D model which represents the workpiece shape to display the workpiece machined shape (for example, see Patent Literature 2).
In this regard, if using a ball end mill or other rotary tool to cut the workpiece surface, the workpiece surface is intermittently cut by the cutting blade. For this purpose, the machined workpiece surface is formed with a large number of spherically shaped dimples along the tool path. However, the systems according to Patent Literatures 1 and 2 only display machining marks formed on the workpiece machined surface as groove shapes along the tool paths, and do not display images which correspond to the actual machining marks (dimples) of the workpiece machined surface. Therefore, a user has found it difficult to obtain a grasp of the surface pattern after machining of the workpiece in advance.